Automatic take-up for rocker arms



July 24, 1934. H WELLS ET AL 1,967,918

AUTOMATIC TAKE-UP FOR ROCKER ARMS Filed March 5, 1932 Patented July 24,1934 7 1,967,918 AUTOMATIC TAKE-UPFOR ROCKER ARMS Harry B. Wells andEdward E. Brown, Ferndale, Mich.

Application Marchv5, 1932, Serial No. 597,020

2 Claims.

This invention relates to the valves of internal'combustion engines andparticularly to means for operating the rocker'arm of avalve-in-thehead'motor.

The general object of the present invention is to provide means forautomatically shifting the rocker arm with relation to the operating camand to the valve stem so that at all times any gap between the end ofthe rocker arm and the valve stem may be automatically kept closedto'thus hold the extremity of the rocker arm or tappet in closeengagement at all times with the valve stem and to eliminate the noisecaused by the impact of the rocker arm against the valve stem.

A further object is to provide a construction of this character whereinthe fluid pressure acts to secure this take-up action.

Other objects will appear in the course of the following description.

Our-invention is illustrated in the accompany ing drawing, wherein:-

Figure 1 is a sideelevation partly in section ofa rocker arm, a valvestem and the cam rod for operating the arm, the parts being shown in aposition wherein the extremity of the tappet or arm is spaced from thevalve stem;

Figure 2 is a like view toFigure 1 but showing the operation of thetake-up means and showing the gap between the valve stem. and the tappetarm closed;

Figure 3 is a section on the line ure 2.

Referring to these figures, designates a valve 35 stem of an internalcombustion engine. This valve stem is shown diagrammatically as theparticular character of the valve stem has no immediate bearing on thepresent invention. 11 designates the usual cam rod by which the usualrocker arm is oscillated, this cam rod being actuated by a cam not shownand at its upper end being provided with a fork 12 designed to beconnected to the rocker arm and with a nut 13 whereby this adjustmentmay be made. So far all of the parts which we have described are old andwell-known. The rocker arm 14 may be of any suitable type and at one endis formed on its under face with the rounded boss 15 adapted to engagewith the extremity of the stem. This rocker arm is oscillatably mountedupon an oil pipe 16 having an outlet port 17. The oil pipe is connectedto any suitable source of fluid under pressure and it is to beunderstood that there are as many rocker arms mounted upon the oil pipeas desired.

3-3 of Fig- In order to automatically and yieldingly hold the end of therocker arm at all times against the valve stem and take up any gapbetween the upper end of the valve stem and the boss of the rocker arm,we form in cam rod en aging end of the rocker arm the bearing 18 anddispose within this bearing'the eccentric 19. This eccentricis rotatabiymounted on a pin 20 which extends into the forks of the clevis 12. Inthe drawing a designates the center of the bearing 16 and b the axis ofthe eccentric in the center of pin 18. The eccentric is formed upon aportion of its periphery with the gear teeth 21, these teeth extendingradially with reference to the center of the eccentric. The bearing 18opens into a downwardly and forwardly inclined chamber 22. Formed in therocker arm immediately beneath the port 17 is a second chamber 23 intowhich the port 17 opens, this second chamber being connected to thebottom of the chamber 22 by means of the passage 24. A valve seat isformed at the lower end of the chamber 22 and a ball valve 25 isdisposed on this valve seat. Any check valve may be used for thispurpose, the purpose being to allow the entrance of liquid into thelower end of the chamber 22 to prevent the rearward movement of theliquid. The outer endof the chamber 23 is closed by a plug 26 anddisposed within the chamber 22 is a movable rack 27 having teeth whichengage with the gear teeth 21.

For the purpose of shifting the rack 27 outward,we disposed within thechamber22 the coiled compression spring 28 which does not bear againstthe check valve but surrounds the check valve and bears against the endof the chamber exteriorly of the check valve. This spring 28 at itsouter end is disposed within the recess in the inner extremity of therack 27 and urges this rack outward. This spring in addition to theweight of the rod 11 acts to urge the piston or rack 2'7 outward and theoil in the chamber prevents a return movement of the rack 27.

The operation of this mechanism is as fol lowsz-In Figure 1, the cam rod11 is about to move downward on its initial stroke. The centers 119 aand b of the eccentric bearing and of the pin 20 are in an approximatelyhorizontal plane with relation to each other. As the push rod movesdownward, the pin 20, which is free to rotate and the eccentric mountedthereon will move to the position shown in Figure 2 with the center I)of the pin disposed below the center a of the eccentric. The eccentric,in other words, will rotate from the position shown in Figure 1 to thatshown in Figure 2.

This rotation of the $1 eccentric will be secured by the outwardpressure there by the check valve 25.

As the cam rod 11 moves downward, therefore,

the pressure behind the rack 27 will cause it to move outward toward theposition shown in Figure 2 and this will rotate the eccentric so as tolift the eccentric end of the rocker arm 14 and depress the toe of therocker arm to bring it in contact with the valve stem 107 Thus as thecam rod descends, the left hand .end of the rocker arm, as shown inFigure 1, will also move downward and the small gap between the boss onthe left hand end of the rocker arm and the valve stem will be closed.Thus when the cam rod has fully descended, the opposite end of therocker arm will still bear against, though it will not depress, thevalve stem 10. When the cam rod 11 rises, however, the oil which hasbeen trapped by the check valve within the chamber 22 will prevent anyreverse movement of the rack 27 and, therefore, the upward movement ofthe cam rod 11 will depress the toe of the rocker arm and depress thevalve stem.

It is to be understood, of course, that if at any time there is a gapformed between the toe of the rocker arm and the valve stem, thepressure behind the rack will cause the further outward movement of thepiston-like rack 27 which will turn the eccentric still more, thustaking up the gap. Thus the rack will at all times be urged upward andany wear will be constantly taken up and the rocker arm held in contactwith the valve stem ll), thus eliminating any noise due to an impactbetween the right hand end of the :rocker arm and the valve stem andtaking up all :play between these parts.

Of course, it will be understood that the Valve stem 10 is urged upwardby the usual spring which holds the valve to its seat and the pressurewithin the oil pipe 16 is not sufiicient to cause any depression of thisvalve stem 10 against the action of the spring. It is only when a gap isformed between the toe of the rocker arm and the valve stem that theliquid under pressure acts to force the rack outward.

While we have heretofore referred to this device as being particularlyadapted for use in connection with the tappets or rocker arms ofinternal combustion engines, we do not wish to be limited to this as theinvention might be used on any power driven mechanism where a rocker armor tappet is necessary and where a take-up between the rocker arm andtappet rod is required.

Such mechanism is often used in pumps and steam engines.

While we have illustrated certain details of construction andarrangements of parts, it will be understood that many minor changesmight be made in the details without departing from the spirit of theinvention as defined in the appended claims.

1. In a structure of the character described, a stem, an oscillatablerocker arm coacting therewith, an oil feed pipe having oil therein underpressure and on which the rocker arm is mounted for oscillation, one endof said arm approximating the stem, the opposite end of the arm having abearing, an eccentric disposed in the bearing and having gear teeth, apush rod having a pin upon which the eccentric is mounted for rotation,the eccentric having its axis displaced radially relative to the axis ofthe bearing, the rocker arm being formed to provide a chamberintersecting said bearing, a rack disposed in said chamber andconstituting a piston, the rack engaging the teeth on the eccentric,said chamber at its inner end having communication with the oil feedpipe, a check valve in the inner end of the chamber permitting theinflow of liquid into the chamber but preventing the outflow thereof,and a spring urging the rack outward.

2. In an engine, a valve, a valve stem, an oscillating rocker armcoacting therewith, an oil feed pipe on which the arm is mounted foroscillation, one end of the arm approximating the valve stem, theopposite end of the arm having a square bearing, an eccentric disposedin said bearing and having teeth on its periphery, a cam rod hav ing apin upon which the eccentric is mounted for rotation, the axis of theeccentric being displaced radially relative to the axis of the bearing,the rocker arm being formed to provide a chamber intersecting saidbearing, a piston-like member disposed in the chamber and having rackteeth engaging with the teeth on the eccentric, the rocker arm beingformed to provide a sump communicating with the interior of the oilpipe,

the sump communicating with the inner end of the chamber, a check valvedisposed at the inner end of the chamber and permitting the how ofliquid from the sump into the chamber but preventing the reverse flowthereof, and a spring 1 disposed Within the inner end of the chamber andbearing against the inner end of the pistonlike member and urging itoutward.

HARRY H; WELLS.

